Solid-state lighting devices such as light-emitting diodes (LEDs) can provide for efficient and versatile light sources. Characteristics of the light emitted by such lighting devices, such as chromaticity, can be adjusted by utilizing light-converting materials, such as phosphors. As an example, white light LEDs can be manufactured by applying a yellow emitting phosphor coating to a blue or ultraviolet “pump” LED, respectively. Light from the pump LED is absorbed by the phosphor, causing the phosphor to re-emit light at a different characteristic wavelength. The perceived colour of combined light from the LED and phosphor coating may thus be adjusted to a desired white. A variety of methods for providing light of a desired chromaticity are known.
The reliable manufacture of lighting devices utilizing solid-state light sources in combination with light-converting materials faces several challenges. Firstly, light-emitting elements such as LEDs typically exhibit substantial variation in chromaticity and other characteristics, both within and between manufacturing batches. Secondly, properties of light-converting material as well as the disposed quantities thereof exhibit fluctuations that can be poorly controlled in conventional manufacturing processes. Conventional manufacturing processes usually dispense phosphors suspended in a binder solution of silicone into a cavity engulfing the LED(s), thereby providing limited control over composition and disposition of adequate amounts of phosphors. Such processes consequently provide poor control over conversion efficiency and chromaticity variations of the generated light. Moreover, unused binder solution typically ends up as waste because recycling of phosphors from typical binder solutions is prohibitively expensive. Typically, manufacturing costs are therefore unnecessarily high when phosphors are wasted that include expensive rare earth elements.
As a result, existing methods for producing solid-state lighting devices incorporating light-converting materials can exhibit significant variation. For example, existing bulk manufacturing processes for producing white phosphor coated LEDs typically provide LEDs which may significantly and perceptibly vary with respect to chromaticity, which necessitates testing and binning of the LEDs. Manufacturing yields are thus reduced by variations in the source materials and variations due to the phosphor coating process. Therefore, there is a need for a method and apparatus for coupling solid-state light-emitting elements with light-converting materials that is not subject to one or more of the above limitations.
U.S. Pat. No. 5,521,035 discloses methods for preparing color filter elements using laser induced transfer of colorants with associated liquid crystal display devices. Color filter elements are prepared by the laser-induced transfer of colorant from a color donor to a transparent, non-birefringent substrate such as glass or polymeric film.
U.S. Pat. No. 5,171,650 discloses a method and system for creating and transferring a pattern from a composite ablation-transfer imaging medium to a receptor element in contiguous registration therewith. The method is applicable for color proofing and printing, security coding, graphic arts and printed circuit industries. The composite imaging medium comprises a support substrate, one or more dynamic release layers, and an imaging radiation-ablative carrier topcoat, which includes an imaging amount of a contrast imaging material. The dynamic release layer absorbs radiation to effect the imagewise ablation mass transfer of the carrier topcoat.
U.S. Pat. No. 7,153,618 discloses a method of forming a color filter substrate of a liquid crystal display device. A black matrix is formed on a substrate, a color filter transfer film is attached to the substrate, and a laser beam is used to irradiate the entirety of the color filter transfer film. The color filter transfer film includes red, green and blue color filter patterns. The transfer film is removed from the substrate such that the red, green and blue color filter patterns remain on the substrate.
This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present technology. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present technology.